I've been reading on different forums and hearing on tv programmes about relationships, where guys say they think there partner is having an affair because of seeing something in her panties???? Is this true can you tell if a woman has had sex from what's in her panties when she takes them off?

If you know what they look like ordinarily, then yes, possibly. But only if she isn't using a condom with the other man (which is unlikely if it's an affair), and only if she isn't having regular unprotected sex with you as well. I would count it as an unreliable indicator.

These mountains that you are carrying, you were only supposed to climb.